Generally, the initial focus during development of a biologically active agent is the physiochemical properties of the pharmaceutical compound, in particular the therapeutic function of the compound. Once the biological activity of the active agent is defined, the design focus typically shifts to the systems and formulations by which the active agent is delivered. In particular, one focus during development of delivery systems and formulations is the provision of a system or formulation in which therapeutic titers of the active agent are able to reach the appropriate anatomical location or compartment after administration.
The phrase “route of administration” refers to the path by which an active agent is brought into contact with the body and is determined primarily by the properties of the active agent and by the therapeutic objectives. The route of administration that is chosen for a particular active agent may have a profound effect upon the speed and efficiency of the active agent upon administration.
In general, routes of administration can be classified by whether the effect is local or systemic. For local delivery, an active agent is applied directly to the tissue or organ for which treatment is sought. The effect of local delivery is limited primarily to the tissue or organ to which the active agent is applied. For example, local delivery may be accomplished through the use of compositions such as liniments, lotions, drops, ointments, creams, suppositories, emulsions, solutions, suspensions and the like. Local delivery can also be accomplished using special delivery devices such as catheters, syringes or implantables designed to convey drug to a specific region in the body. In contrast, an active agent administered systemically enters the blood or lymphatic supply and may be felt some distance from the site of administration. For systemic delivery, oral and parenteral routes are typically used.
However, there is still a need in the art for simple, inexpensive delivery systems which are easily prepared and which can deliver a broad range of active agents to their intended targets, especially in the case of hydrophobic active agents.